1. Field of the Invention
The present invention relates to a sleeve to be installed on the reel of a winding or rewinding machine to prevent the production of flaws in a steel strip while the steel strip is wound or rewound, after processing of the steel strip through hot rolling, cold rolling, surface treatment, etc.
2. Description of the Related Art
In the past, sleeves have been installed on the outer periphery of a reel to prevent the production of top flaws (step-type flaws) on the surface of the strip while the strip is wound on the reel of the winder. Top flaws are generated when the second turn of the strip is wound, and thereby stacked on the edge of the already wound strip. Such flaws become gradually smaller with an increasing number of wound layers, and eventually disappear.
Sleeves have also been installed to prevent the generation of slip flaws which are produced on the steel strip surface during winding or rewinding. These flaws result from a difference in linear velocity between the steel strip and the reel surface, or between layers of the steel strip.
Sleeves may be constructed of rubber alone or rubber embedded with synthetic resin at places. They may also be formed from a layer in contact with the steel strip, which is made of craft paper or synthetic resin. Some reels have a special configuration at the surface in contact with the steel strip. Other sleeves are made up of multi-layers.
When oil is applied to a steel strip, however, slip flaws may be produced in spite of the installation of the sleeve, because of the slippage occuring between the steel strip and the sleeve surface. Therefore, in such a case, the sleeve surface which is in contact with the reel and/or the surface of the steel strip must be washed well.
Alternatively, corrugated fiberboard, etc., may be inserted between the reel and the steel strip or between the sleeve and the steel strip to prevent the slippage. However, the prevention of slippage is not certain by this method, and a long time is required to attain the necessary tension for winding, and workability, profitability as well as safety have been poor in such cases.
In view of the above, it is evident that a need continues to exist for new types of sleeves which are capable of preventing flaws in steel strips during winding.